The veteran star won an Oscar for her role as the practically perfect nanny in the 1954 classic film but turned down the chance to make a cameo appearance in the follow-up Mary Poppins Returns, which stars Emily Blunt in the tile role.

Director Rob Marshall told the Press Association: "I know her very well, she's a very good friend and early, early, early on, before we started writing, I spoke to her about it.

"I told her who was playing Mary Poppins and she threw her arms up in the air and said 'I love her'. She has very good taste, I agree."

Then I started talking about the possibility, should we write something for you? Would you like to be involved? And she said 'Oh no no no, this is Emily's show, she needs to run with it' and she was so right about that, she really was.

"It was a very generous thing to say and smart because she knew we need to see this Mary Poppins and accept this Mary Poppins, and she's pretty special, Julie.

"Marshall, who also directed Into The Woods and Chicago, said Dame Julie has given her verdict on the new offering, saying: "She's seen it, she said 'I loved it' in huge capital letters and the email that she sent was literally I can't tell you how long and about everything.

"[It was] about Emily, she said Emily was wonderful, she loved her voice, she loved every single person in the cast, she was just over the moon about the whole thing, I was relieved and thrilled."

Mary Poppins (Image: Getty)

The film does include a cameo from Dick Van Dyke, 93, who played chimney sweep in the original film and Marshall said: "I called him and I asked him, and it was just a dream come true to be able to talk to my literally childhood hero, and he is so joyous and so alive and so young.

"His youth is unbelievable, so to have him on this film was a joy. He actually grabbed my hand as we were walking on to the set and he literally said to me 'I feel the same spirit here on this film as I did on the first one and that was something special'.

He added: "When they came to me with it I really wanted to take it on, even though I was daunted by the idea of it because I love the first film so much as everybody pretty much does in the world.

"I did feel if it was going to be done I wanted to do it, I wanted to be that person who was ushering in the spirit of that beautiful first film into our film and at the same time create something completely new, an original musical, so it was a real balancing act the whole time."